Is Psychology a science?: Redux

The third-most read post on this blog is "Is Psychology a science?". I was a few years younger then and still had strong memories of one of my friends complaining, when we were both undergraduates, that he had to take a psychology course as part of his science distributional requirements. "Psychology isn't a science," he said, "because they don't do experiments." Since he was telling me this over AIM as I was sitting in my psychology laboratory, analyzing an experiment, it didn't go over well.

It's been a popular post, but I haven't written about the subject much since in part because I started to suspect that the "psychology isn't a science" bias might actually be a thing of ignorant undergraduates and a few cranks. It's not something I've rarely heard in the last few years, and there's no need to write diatribes against a non-existant prejudice.

In retrospect, maybe I haven't come across these opinions because I mostly hang out with other psychologists. A colleague recently forwarded me this blog post ("Keep Psychology out of the science club"), which links to a few other similar pieces on blogs and in newspapers. So it seems the issue is alive and well.

Some articles one comes across are of the "psychologists don't do experiments" variety; these are easily explained by ignorance and an inability to use Google. But some folks raise some real concerns which, while I think they are misplaced, really are worth thinking about.

Psychology is too hard
One common theme that I came across is that psychology is simply too difficult. We'll never understand human behavior very well, so maybe we shouldn't even try. For instance, Gary Gutting, writing in the Opinionator at the New York Times, said:

Social sciences may be surrounded by the "paraphernalia" of the natural sciences, such as technical terminology, mathematical equations, empirical data and even carefully designed experiments. But when it comes to generating reliable scientific knowledge, there is nothing more important than frequent and detailed predictions of future events ... while the physical sciences produce many detailed and precise predictions, the social sciences do not ... Because of the many interrelated causes at work in social systems, many questions are simply "impervious to experimentation" ... even when we can get reliable experimental results, the causal complexity restricts us...

The NSF shouldn't fund any social science. Federal funding for mathematics, engineering and other "hard" sciences is appropriate. In these fields, researchers can test their hypotheses under controlled conditions; then those experiments can be repeated by others. Though quantitative methods may rule economics, political science and psychology, these disciplines can never achieve the objectivity of the natural sciences. Those who study social behavior -- or fund studies of it -- are inevitably influenced by value judgments, left, right, and center. And unlike hypotheses in the hard sciences, hypotheses about society usually can't be proven or disproven by experimentation. Society is not a laboratory.

Making useful predictions is a vital part of the scientific process, but psychology has a dismal record in this regard.

Is that a fair critique?
These writers don't entirely miss the mark. It really is true that psychology does not make as precise or as accurate predictions as, say, physics. That is not the same thing as saying that we can't make any predictions. Berezow complains about happiness research:

Happiness research is a great example of why psychology isn't a science. How exactly should "happiness" be defined? The meaning of the word differs from person to person, and especially between cultures. What makes Americans happy doesn't necessarily make Chinese people happy. How does one measure happiness? Psychologists can't use a ruler or a microscope, so they invent an arbitrary scale. Today, personally, I'm feeling about a 3.7 out of 5. How about you? ... How can an experiment be consistently reproducible or provide any useful predictions if the basic terms are vague and unquantifiable?

That's a great question! Let's start with the facts. It is true that we don't know exactly what it means to be a 3.7 on a scale of 1-5. But we do know a few interesting things.

People's predictions of how happy they will rate themselves in the future are systematically biased. People will say that good things (like getting tenure) will make them very happy (a 5 out of 5) whereas bad things (like not getting tenure) will make them very sad (a 1 out of 5), whereas when you then ask those same people to rate their happiness a little while after the event, people generally rate themselves as not nearly so happy or unhappy as they predicted. (Similarly, people who lose a limb usually rate themselves as about as happy afterwards as before, provided you give them a little time to adjust.) People who have children normally see a drop in how happy they rate themselves. They only start to recover after their children leave the nest. There is also the "future ahedonia" effect: people think that good things (e.g., an ice cream sunday) will make them happier now (on our 1-5 scale) than those same good things would make them happy in the future, and conversely for bad things (e.g., doing my homework won't feel so bad if I do it tomorrow rather than today). And so on. (These and many other examples can be found in Dan Gilbert's Stumbling on Happiness.)

These and other findings are highly reliable, despite the fact that we don't have a direct, objective measurement of happiness. In fact, as Dan Gilbert has pointed out, we would only consider that "direct" measurement to be a measurement of happiness if it correlated really well with how happy people said they were. To the extent it diverged from how happy people claim to be, we would start to distrust the "direct" measurement.

I personally am glad that we know what we know about happiness, though I wish we knew more. I picked happiness to defend because I've noticed that even those who defend psychology in comments sections give up happiness research as a lost cause. I think it's pretty interesting, useful work. It would be even easier to defend, for instance, low-level vision research, which makes remarkably precise predictions, has clear theories of the relationship between the psychological phenomena and the neural implementations, etc. (See also this post for some psychology success stories.)

Just how good do you need your predictions to be?

Still, it is true that we can't always make the precise predictions that can be made in some other fields. Of course, other fields can't always make the precise predictions, either. While physicists are great at telling you what will happen to rigid objects moving through vacuums, predicting the motions of real objects in the real world has been traditionally a lot harder, and understanding fluid dynamics has been deeply problematic (though I understand this has been getting a lot better in recent years). And that's without pulling out the Heisenberg Uncertainty Principle, which should cause anyone who wants precise, deterministic predictions to declare physics a non-science.

Also, some parts of psychology are able to make much more precise predictions than others do. Anything amenable to psychophysics tends to be much more precise, and vision researchers, as already noted, have remarkably well worked-out theories of low- and mid-level vision.

This line of discussion also raises an interesting question: when exactly did physics become a science? Was it a science in Newton's day, when we still new squat about electromagnetism -- much less elementary particles -- and couldn't make even rough predictions about turbulent air or fluid systems? And to people from 350 years from now, will the physics of today seem like a "real" science (my guess: no).

Worries

Berezow ends his post with the following caution:

To claim [psychology] is a "science" is inaccurate. Actually, it's worse than that. It's an attempt to redefine science. Science, redefined, is no longer the empirical analysis of the natural world; instead, it is any topic that sprinkles a few numbers around. This is dangerous, because, under such a loose definition, anything can qualify as science. And when anything qualifies as science, science can no longer claim to have a unique grasp on secular truth.

I have a different worry. My worry is that someone gets ahold of a time machine, goes back in time to 1661 and convinces Newton to lay off that non-scientific "physics" crap. Pre-Newtonian physics was a hodgepodge of knowledge, little resembling what we think of science today. Making precise predictions about the messy, physical world we live in no doubt seemed an impossible pipe-dream to many. Luckily, folks like Newton kept plugging away, and three and a half centuries later, here we are.

We should keep in mind that the serious study of the mind only began in the mid-1800s; physics has a significant head-start. And, as the anti-psychology commentators are happy to point out, psychology is much, much harder than physics or chemistry. But the only reason I can see to pull the plug is if we are sure that (a) we have learned nothing in the last 150 years, and (b) we will never make any further progress. These are empirical claims and so subject to test (I think the first one has already been falsified). So here's a proposed experiment: psychologists keep on doing psychology, and people who don't want to don't have to. And we'll wait a few decades and see who knows more about the human mind.

2 comments:

Anonymous
said...

I really like this quote from Simon, "The true line is not between “hard” natural science and “soft” social sciences, but between precise science limited to highly abstract and simple phenomena in the laboratory and inexact science and technology dealing with complex problems in the real world."

I'm not sure if I agree. We'd need a definition of "simple phenomena" that included quantum mechanics but excluded a number of fairly simple psychological phenomena (like discounting curves).

Also: I just spent a week visiting a high school friend who is now a physicist who pointed out that in a number of areas of physics, there aren't good mathematical theories, so folks have to rely on rules-of-thumb, which sounds an awful lot like the state of the behavioral sciences.

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The focus of lab and blog is language -- what it is, how we understand it, and what we can do with it. At the blog, we discuss research, findings and controversies. At the lab, we try to create new research, findings and controversies.